Ethan Couch, the "affluenza" teen from Texas believed to be on the run for a possible probation violation, was found with his mother in Mexico.

Authorities said Ethan Couch, 18, and Tonya Couch, 48, were detained in Puerto Vallarta, after searching for them since Dec. 16, reported the Fort Worth Star-Telegram.

Tarrant County Sheriff Dee Anderson said he believed Ethan Couch was on the run because he was under investigation for an online video that showed him clapping with friends while playing beer pong, a possible violation of his probation.

A $5,000 reward was offered for information on Couch's location after the U.S. Marshals Service issued a wanted notice for the teen, said the Dallas Morning News. Authorities listed Tonya Couch as a missing person after Ethan Couch could not be found.

A photo of Couch with dark hair was released by Jalisco State authorities Tuesday morning.

In 2013, Couch admitted to a drunk-driving crash that killed four people, said NBC News. A psychologist testified that the teenager suffered from "affluenza" because of his privileged upbringing and didn't understand right from wrong. Affluenza is not recognized by the American Psychiatric Association as an official diagnosis.

Couch was 16 at the time of the crash and had a blood-alcohol level almost three times the legal limit.

State District Judge Jean Boyd, who is now retired, sentenced Couch to 10 years of probation on four counts of intoxication manslaughter in the crash, said the Star-Telegram. Prosecutors wanted Couch to serve 20 years behind bars.

The Morning News said a judge was expected to rule on a request to move Couch's case from juvenile court to adult court after Couch turns 19 in April.